Qiyas — Analogical Reasoning in Islamic Law

Definition

Qiyas (قياس) is analogical reasoning, the fourth source of Islamic law. It extends a ruling from an established case (asl) to a new case (far') based on a shared effective cause (illah). When the Quran or Sunnah explicitly addresses one situation but a new, similar situation arises, qiyas allows scholars to apply the same ruling if the underlying reason for the original ruling is present in the new case. Imam al-Shafi'i established qiyas as a formal methodology in his Risalah.

Components of Qiyas

Valid qiyas requires four elements. The asl (original case) is the situation with an established ruling from the Quran, Sunnah, or ijma. The far' (new case) is the situation needing a ruling. The hukm (ruling) is the legal judgment being extended. The illah (effective cause) is the reason or attribute that links the two cases. For example, the Quran prohibits wine (asl). The illah is intoxication. Any new beverage (far') that causes intoxication receives the same prohibition (hukm). The identification of the correct illah is the most critical and debated step.

Conditions and Limits

Qiyas is valid only when certain conditions are met. No direct text from the Quran or Sunnah should address the new case. The illah must be identifiable, consistent, and applicable to both cases. Qiyas cannot override a clear text or established consensus. It does not apply to matters of pure worship (ibadat) where the reasons are not accessible to human understanding. The Hanbali school historically gave less weight to qiyas, preferring weak hadith over analogy, while the Hanafi school used it most extensively.

Significance

Qiyas enables Islamic law to address new situations across time and place without abandoning its textual foundations. From medieval questions about new commercial instruments to modern issues in bioethics and technology, qiyas provides a principled method for extending divine guidance to human circumstances the original texts did not explicitly address. It demonstrates that Islamic law is not a static code but a living methodology capable of engaging with every era while remaining rooted in revelation.